Structure–activity relationships of cyclic and linear peptide T analogues

Abstract
Using the potent cyclic peptide T analog‐Thr‐Thr‐Asn‐Tyr‐Thr‐Asp‐ as parent compound, a series of analogues were synthesized and their potencies in a monocyte chemotaxis assay were compared with those of correspondingly modified linear peptides. Structure‐activity relationships observed with cyclic compounds did not always parallel those determined with linear analogues. ‐Thr‐Hse‐Asn‐Tyr‐Thr‐Asp‐ showed the highest affinity to CD4 receptor of monocytes of any peptide thus far studied. It also proved to be highly resistant to degradation by plasma or brain enzymes.